Enamel thickness measurement with a high frequency ultrasonic transducer-based hand-held probe for potential application in the dental veneer placing procedure.

This study presents a novel approach to measure the enamel thickness potentially applicable to the veneer placing procedure. All experiments have been carried out on the extracted human teeth, using a high frequency ultrasonic transducer (50 MHz, Sonix, Springfield, VA, USA). The enamel thickness measurement results obtained with high positional accuracy by a scanning acoustic microscope (Tessonics AM1103, Windsor, ON, Canada) were compared with the measurements conducted in a hand-held mode by using the same transducer placed in a custom fixture. Finally, to validate the ultrasonic measuring results, the samples were cut down the long axis to expose the cross-section. The enamel thickness was measured in several points along the selected part of the exposed cross-section by using an optical microscope (Stemi SV 11, Carl Zeiss AG, Jena, Germany). The values of the enamel thickness received by using the hand-held probe vs. the acoustic microscope were in close proximity (~10% difference) and were also satisfactory close to the enamel thickness results obtained from the direct cross-sectional measurements (~12% difference). The authors suggested a measuring procedure that allows avoiding errors related to the ultrasonic beam localization on the tooth surface. The high feasibility of the ultrasonic pulse-echo measurements in a hand-held mode was demonstrated.